Australian enduro racer Josh Carlson in a product testing session in Oregon on a prototype version of the Trance Advanced 27.5.

We got a sneak peek at some of the new 27.5 bikes from Giant back in April and Giant has now released all the bikes and information to the masses. What is most interesting is that Giant has jumped in with both feet and they are offering a ton of models in 27.5 including several in their Liv category (women’s specific). With so many models from Giant and several recently announced from Trek, how much longer will the other big brands like Specialized and Cannondale hold out?

Check out the official info below including their World Cup racing development and science behind the 27.5 line of bikes!

From the Manufacturer: Giant 27.5 Ride Without Limits.

The off-road world now has three wheel sizes from which to choose. Through extensive research and ride testing, Giant has thoroughly analyzed how each size performs under different riding styles and in varying conditions. Our findings show that mountain bikes with 27.5-inch wheels deliver superior performance without the compromises of 26 or 29-inch-wheel bikes. So to create the best off-road riding experience, Giant has fully committed its 2014 lineup to this superior technology.

Marianne Vos of the Rabobank-Liv/giant team, the current world and Olympic champion on the road, helped develop the Obsess Advanced. She rode a prototype version at several World Cup events this year as she begins her bid to race cross-country at the next Olympic Games.

The Intrigue series, designed for aggressive trail and enduro riding, features an ALUXX SL aluminum frame optimized for 27.5 inch wheels and 5.5 inches of Maestro Suspension technology. The Intrigue 1 shown here features a dropper seatpost with a handlebar remote and internal cable routing.

Why 27.5?

There is a common misconception that the performance of 27.5 technology sits squarely in the middle between 26 and 29. But as our data reveals, 27.5 actually displays some of the best characteristics of 26 and 29—and it never measures out exactly in the middle.

When it comes to weight, 27.5 performs more like 26—it’s light and agile. And for efficiency and control, it outperforms 29. Rather than introduce a single 27.5 model, as some of our competitors have, Giant is rolling out entirely new designs and engineering solutions to maximize the performance advantages of 27.5-inch wheels. Here’s why:

27.5 Technology: 3 Reasons to Believe

1. Lighter Weight

27.5-inch wheels are only 5 percent heavier than 26-inch. By comparison, 29-inch wheels are 11 percent heavier than 26-inch.

Overall weights of 27.5 bikes also trend closer to 26 than heavier 29 versions of the same series

Every rider experiences two types of weight affecting their ride: overall bike weight and rotational wheel weight. Here’s a closer look at these two forces and how different wheel sizes alter the dynamics of your ride:

Overall Bike Weight
Compare the weights of identically equipped bikes with different wheel sizes and you’ll see substantial weight differences. As expected, the 26-inch-wheel bike is somewhat lighter than the 27.5, and substantially lighter than the 29 (up to two pounds of overall bike weight savings from 29 to 27.5). Every gram saved helps you ride faster.

Wheel/Tire Weight
The overall weight of a 27.5 wheelset (wheel, tire and inner tube) is only 5% greater than that of an identically built 26-inch wheelset. Compare this to the 12% increase of a 29-inch wheelset and you can see how a seemingly small increase in diameter results in substantial weight gain—and poorer performance when climbing or accelerating.

27.5 wheels accelerate much like 26, outperforming the more sluggish feel of 29-inch wheels.

27.5 wheels roll over obstacles with much more control than 26. That translates into more efficient cornering, acceleration and braking capabilities.

Rollover
Increased wheel diameter decreases the angle of attack (the angle in which a round object intersects a square object). This is a good thing. A 29-inch wheel rolls over a 6-centimeter square-edge obstacle 14% more efficiently than a 26-inch wheel does. In comparison, a 27.5-inch wheel rolls over the same obstacle 9.8% more efficiently than a 26-inch wheel does. Another way to analyze angle of attack is the degree of impact—where 26-inch equals X degree, 27.5 equals X-4 degrees and 29 equals X-6 degrees. Again, a shallower angle is better—so 29-inch takes the win, with 27.5 exhibiting nearly the same performance but without the weight penalty.

Acceleration
Arguably the most important benefit of 27.5 over 29 is quicker acceleration. This is the “snap” that a rider feels when they push hard on the pedals. It is affected not just by overall static weight but also where the weight is distributed throughout the wheel. The farther the weight is from the center of the hub, the slower the acceleration. So a similarly constructed 1000-gram 29-inch wheel is slower to accelerate than a 1000-gram 26-inch wheel—because the larger diameter rim and longer spokes place weight farther from the hub. The key to snappy acceleration is minimizing the weight of the outermost components (rim, nipples, spokes, tire, tube). As you can see, a 27.5-inch wheel is only 1.5% slower to accelerate than a similarly constructed 26-inch wheel, but a 29-inch wheel is 3.6% slower than a similarly constructed 26-inch wheel.

3. Better Control

The larger the diameter of a wheel, the greater the contact patch of the tire. A larger contact patch results in better traction—which improves acceleration, deceleration and cornering. 27.5 wheels provide a contact patch that is similar to 29-inch wheels.

The larger the wheel, the larger the frame dimensions must be—and that leads to unwanted flex. A flexing frame causes sloppy handling and slower acceleration under heavy power. A 27.5 frame flexes less than a 29 frame, resulting in better control.

Traction
The larger the diameter of a wheel, the greater the contact patch of the tire. A larger contact patch results in better traction, which leads to improved acceleration, deceleration and cornering. As you can see below, a 27.5-inch wheel has a similar contact patch to the 29.

Frame Geometry
The larger the wheel, the more difficult it is to optimize geometry, especially on smaller frames. As the frame size decreases, headtube heights become higher (in relation to saddle height). On 26 or 27.5-inch frames, it’s less of a problem, but geometry limitations can affect smaller 29-inch-wheel frames.

Continue reading for more information, specs, pricing and full photo gallery of the new 2014 Giant and Liv/giant 27.5 models.

Gregg Kato studied journalism and broadcasting in college while working many different jobs including deejaying, driving a forklift and building web sites (not all at the same time). Kato has been the Site Manager of Mtbr.com for over 14 years and enjoys riding local Santa Cruz trails. Besides being an avid mountain biker, he is also a motorcycle fanatic. Two wheels, one Passion.

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Yeah, right. All the major players needed to segment the market and force us to upgrade/update our bikes because the bikes/frames were so good that we were all happy with our current bike, and nobody was buying a newer model. And yet they want to convince us it was for our own good. I’ve tried four 650b bikes, and in my humble opinion they aren’t as playful and nimble as my 26ers. Now if I’d like to upgrade my frame for a newer model, I’d have to buy a new set of wheels, a new fork, etc.

Cool infomercial, but I still believe this isn’t in our best interests, but in the commercial ones (i.e. maximize revenues) of the bike industry.

Wheel diameter has no bearing upon acceleration. If the rim and tire are the same weight the larger wheel will also be rotating slower; the effects cancel out. In order to get to the same rpm will take more energy, but that’s not the comparative case here.

If you use the same type of rim and tire, the net overall [rotating and non rotating bike plus rider] acceleration loss between 27.5 and 29 is about .15% or one six hundredth difference. Plus the bike will be about a third of a pound heavier.

There may be valid reasons for going 27.5 but noticeable differences in acceleration are hard to measure.

A smaller diameter wheel in effect changes the “final drive ratio”…. and 1.5″ most certainly would make a difference.

But dont take my word for it, just google “rolling diameter” and its effects on acceleration- and you will quickly find a lot of motor racing references proving my point. 1″ bigger on a car makes a difference…. so on a bike with only your own 2 legs, its even more noticeable.

What the fail to mention is that all the slight differences in percentage points we because 650b isn’t really a 27.5 more like 27.125 making there arguments moot. Imma hold out for the 31ers. Now that’s a monster truck mobbing down the trail.

I did notice a BIG difference from 26 to 29. The 29 doesent handle well in twisty sections, Its seems to make me go slower. But it also seems like I can climb up hills and ride rock gardens with less effort on a 29.

What a $%^&*#@ load. 2% here, 1.5% there. Here’s a stat for you, 95% of riders out there with suspension forks don’t even know what their settings are, they just ride. All of this sounds like an attempt to over hype bikes that will ride poorly.

I tried a 650B frnt wheel with good results over 3 years ago. Also found that many cross country racers were secretly using this combo on some courses with great effect (some in spite of sponsors not having a 27) .
Three years later I have given away a 29er, only will ride my 26 as an indoor trainer!
On my third 27.5 conversion, & find them completely superior to the original designed for 26, except climbing on pavement!
Finally as Scott won almost every 2012 cup race with a 650 (they did-NOT even have a 650 production bike at the time!) & many other XC wins later (Sea Otter 2013), I can have a 5″ travel bike made for 27.5!!!
Ride what you like, but I will never ever ride a 26er off-road again!

Here is what it comes down to: Ride the bike. If it fits you and “disappears” underneath you then buy it. Who cares what wheel size? I compared the Santa Cruz Bronson, the Tallboy LTc and Tallboy at a demo day recently. The Bronson felt more balanced and fluid of the 3 bikes. While I loved how the 29r’s rolled through the rock gardens I felt too up in the air on them. (I’m 6’1″) They were amazing and I wouldn’t turn them down, but the Bronson just felt right to me.

being tall in a world designed for the numerical averages, so as to reach / tap a broader market, ALWAYS! leaves the tall people CRAMPED!

Long live the 29ers!

BMX barrowed from the road racers in the late 1970′s and early 1980′s.. same as the MTB crowd.. and the 700c will NEVER! die.. because it is not a FAD! Not that 650b / 27 is a FAD.. because the short people of the World can reach the pedals easier.. and the middle of the road / normal or better yet the numerical average height crowd will feel better moving to a bike that is smaller.. thusly more maneuverable. because none of the men that are 5’5″ to 5″10″ want to ride a Small Frame 29er.. because of the word SMALL! being stuck I their SMALL(ish) Napoleon Complexes, LULZ!

the 650b boils down to the majority of men riding are less than average height, look around on the hill and at the Pros.. what do you see, don’t hate me for speaking the truth!

and these men who are spending money.. ALREADY!! have Small issues.. and thus a Bike with SMALL written on it or more accurately when a woman notices how short in length their top tube is.. some women go around measuring top tubes.. would then laugh openly at the demure size of the little(ish) man with the little(ish) top tube.

why does everyone try to be so Polite to these angry little Napoleon Types?

mean while the tall people.. who are always reaching stuff and being helpful in general.. are stuck being made the bad guys because we had finally an area where we could come together and be clumsy together.. with not a lot of people watching because we would be in the woods where they couldn’t see us being clumsy!

Tall People are being forced out of MTBing! by the little people! they steal everything!

I own a Giant Anthem 26″ custom build and a Giant talon 0 29er
The anthem is my number 1 choice every time its just more fun
I can see the point of a 27.5″ anthem it should be good but I will not be in a rush to get rid of the 26″
back to the talon its spot on for moor rides but it feels a bit dull at the trails
also giants own brand wheels on the cheaper models are not good my 29er wheels lasted 1 winter then I changed them for some mavic crossrides made it a better ride

I was holding out on the 29 er fad as long as I can and I believe it is for taller riders (5’10″) above guys. I am 5’8 and happy with my 26 until i rode a 9er after much hesitation. For starter going over roots and logs got much confident just cause it dint want to trip as easily as my 6er did and this was a hard tail as compared to my 6er full suspension and still the tire size soaked up the bumps and was easier to pedal climbs ! I am still going to hold out for the 27.5 , cause I think vertically challenged rider like myself will have trouble throwing around a 9er like i do with my 6er. But the 27.5 may be a happy medium for guys like me !

I just moved from a Nomad to a Bronson and the 27.5″ are better. Most times I don’t notice them but when doing slow techie rocks they’re way better. Easier to hold a line through sketchy stuff too whether fast or slow, carves berms better, even seems to do skinny north shores better too although I’ve no idea why, and compared to the Nomad, it hops through the All Mountain Trials sections of the track I ride like a trials bike, but that’s probably down to the bike, who knows, and I reckon I ride faster, but it’s sometimes hard to work out if that’s because the bike is so refined or it’s the wheels, but probably a combination of both. End of the day 27.5′s are evolution in progress but that’s not to say that a good bike, regardless of wheel size, will always be a blast to ride, but IMO 27.5′s are more fun to ride than 26′er’s. The only thing I don’t like is that I’ve clipped my balls a few times on the back tyre when hanging off the back of the bike (ouch) but seem to have unconsciously adjusted my riding style as it’s not happened for awhile. I’m thinking that 29′er riders must have problems with the family jewels.
A 27.5″ Nomad would be a game changer I reckon.

Holy s$&t! I was looking for some help in deciding if I should “upgrade” my 14yr hard tail stump jumper … I love that F-er and I feel like I can attack any trail without hesitation. Maybe it’s the engine? But seriously – if I’m having fun attacking the hills on my old 26er … Why the F should I be considering spending a lot of money on a new bike? Somebody shed some knowledge – I am cheap but I invest wisely for long term use! 27.5 or stick to my O.G. ride?

I like that Giant is pushing the envelope and trying something different. It shows a lot of confidence from the brand to step out and try something new.

That said, I’m not 100% positive I agree with the 27.5 as a platform. It makes sense in some applications and regions, but others maybe not. I guess only more testing on the trails will prove to be right or wrong.

Hi All,
I have had 26ers for years and last year got a 29e, they are just too big in tight rutted ground like the peaks etc and at 5’9 i think the bike is just too big even on a medium frame. I am just about to buy a 650B and going for the Giant, it just has it for me cant wait to hit the trails and getting out for a long weekend in Wales 

I just got a 27.5 Giant Talon 4 in a the small frame size since I’m 5′ 7″. It’s acceleration is incredible, boy does it grab and grip and go, although I’ve never ridden a 26 so take my opinion there with a grain of salt. I tested a handful of 29ers, specifically Cannondale, GT, and Marin and just found them to not be as nimble as I like. I feel like I can do laps around a 29er, not really, but you get the idea. Ride with the GIANTS!